To observe diffraction,the size of an obstacle:

Diffraction of light occurs only when the dimension of the obstacle is .....

In a diffraction pattern, light of wavelength $580 \,nm$ is incident normally on a slit of width '$a$'. The distance between the slit and the screen is $2.5 \,m$ and the distance of the second-order maximum from the center of the screen is $14.5 \,mm$. The value of '$a$' is:

In a Fraunhofer diffraction at a single slit,if yellow light illuminating the slit is replaced by blue light,then the diffraction bands

$A$ slit of width $d$ is illuminated by light of wavelength $\lambda$. The angular width of the central maximum is:

In a double slit experiment,the two slits are $1\, mm$ apart and the screen is placed $1\, m$ away. $A$ monochromatic light of wavelength $500\, nm$ is used. What will be the width of each slit for obtaining ten maxima of the double slit pattern within the central maxima of the single slit pattern? .......$mm$